© Springer International Publishing Switzerland 2017Basavana G. Goudra and Preet Mohinder Singh (eds.)Out of Operating Room Anesthesia10.1007/978-3-319-39150-2_17
17. Anesthesia for Procedures in the Neurointerventional Suite
Anesthesiology and Perioperative Medicine, Penn State Milton S Hershey Medical Center, Center for Perioperative Services, 500 University Drive, Hershey, PA 17033, USA
Anesthesiology and Perioperative Medicine, Penn State Milton S Hershey Medical Center, 500 University Drive, Hershey, PA 17033, USA
Procedures in the neurointerventional suite can be divided into opening procedures and closing procedures, such as angioplasty for stroke, embolization for cerebral arterio-venous malformations or coiling for cerebral aneurysm. Different equipment and medications are available for each type of procedure with unique possible side effects and complications.
Anesthesia plans must entail patient and provider safety, including radiation safety. Hemodynamic goals for individual procedures and patients may be very different and should be set and modified as necessary. Neuro-physiological monitoring requires the use and combination of medications that have the least effect on transmitted signals. Neuroprotective measures should be considered. Anticoagulation is often necessary. Various approaches to anticoagulation and reversal are available.
KeywordsNeurointerventionalStrokeCerebral vascular malformationsNeuroprotectionNeuromonitoringAnticoagulationHemodynamic monitoringRadiation safety
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Radiation Technology 
Neuroradiology diagnostic and therapeutic procedures are done under high resolution fluoroscopy plus/minus digital subtraction angiography (DSA).
For DSA, a preliminary film is taken and all the bony structures are subtracted by a computer.
The resultant images only display vessels containing injected contrast material, called a road map.
Road mapping facilitates the placement of microcatheters into the distal circulation.
For accuracy of this technique, the patient must not move and akinesia is a prerequisite.
Ionizing radiation can cause cell death leading to tissue injury, in particular lens opacities, skin injury and infertility. Radiation exposure may also induce cancer neoplasms. Different recommendations exist for dose limits for tissue injury and cancer induction .
Organs most affected are the eyes,-where radiation exposure can lead to cataract formation. Another organ of concern is the pregnant uterus where ionized radiation to the fetus can cause malformations and even fetal demise .
Leaded protection gear should be used, including aprons, shields and glasses.
Leaded glasses should be worn to protect the eyes from developing cataract. Lead glasses provide a higher degree of protection than transparent shields provide, in particular if the anesthesiologist is in close proximity to the patient .
Prescription glasses with glass lenses provide some protection, while plastic lenses provide very little protection.
Material and Equipment
Material Used for Occlusive Procedures, Such as Aneurysm Coiling or AVM Embolization
For procedures that aim at occluding a lesion or structure, such as a cerebral aneurysm or an arterio-venous malformation, different embolic material is available .
Solid embolic material includes coils (usually titanium), Polyvinyl Alcohol (PVA) particles, detachable balloons and gelatin containing sponges (Gelfoam).
Liquid embolic material  includes highly adhesive N-Butyl-Cyano-Acrylate (NBCA) and non-adhesive Ethylene-Vinyl-Alcohol Co-Polymer EVOH (Onyx).
Agents Used for Opening Procedures, Such as Vasospasm Treatment After Sub Arachnoid Hemorrhage (SAH)
Endovascular treatment for SAH induced cerebral vasospasm includes the following procedures and medications :
Percutaneous Transluminal Baloon Angioplasty: PTA is usually limited to proximal vessels with a diameter of more than 2–3 mm.
Possible complications of PTA are reperfusion injury, embolism, thrombosis, displacement of surgical clips and vessel rupture.
Intra-arterial (IA) Pharmacological Therapy
Final effects of IA drug therapy are vascular relaxation and vasodilation. Hypotension and increase in ICP may result from such treatment.
Combinations of the drugs listed below may be used.
Papaverine is a potent nonselective vasodilator.
Intraarterial application reverses cerebral vasospasm.
Papaverine improves CBF, cerebral circulation time and cerebral oxygenation.
Increases in ICP during intra-arterial administration of Papaverine are common, i.e. ICP monitoring during the procedure is recommended.
Other complications include cardiac side effects, thrombocytopenia, hypotension, neurological deficits, loss of visual acuity, mydriasis, and paradoxical worsening of vasospasm.
Phosphodiesterase III inhibitors (Amrinone, Milrinone)
Increase intracellular cAMP levels has positive inotropic and vasodilatory effects.
Systemic effects are rare and have been reported only in case reports. These include increases in heart rate and one case of hypotension requiring dopamine administration.
Increase in CBF has been demonstrated for both amrinone and milrinone.
Calcium channel antagonists (Verapamil, Nimodipine, Nicardipine)
Ca + channel antagonists inhibit Ca + influx into smooth muscle cells and have a vasodilatory effect.
IA administration of Ca + channel antagonists can result in decreases in blood pressure and increases in ICP, particularly at higher doses.
Blood pressure usually returns to normal shortly after stopping an IA infusion.
Vasopressors may be needed to maintain hemodynamic stability during procedures.
Fasudil is a potent vasodilator with relative specificity for cerebral arteries.
Systemic hypotension may occur in addition to small increases in ICP.
Colforsine Daropate HCl
Colforsine increases intracellular cAMP via activation of Adenyl Cyclase.
It has positive chronotropic, inotropic and vasodilatory effects.
Colforsine has been successfully used to treat vasospasm.
Transient changes in heart rate and blood pressure were seen.
Flow Augmentation Strategies
NeuroFlo catheter, Intra-aortic balloon pump (IAPB) counterpulsation.
Intra-aortic balloon catheters can be used to augment cerebral blood flow.
Successful application of the NeuroFlo catheter as well as IABP in patients with cerebral vasospasm has been demonstrated in multiple recent trials
Recanalization of Ischemic Stroke 
The only currently FDA approved therapy for recanalization following ischemic stroke is intravenous tissue plasminogen activator (tPA), given within 4.5 h of onset of symptoms.
Other approaches to address a longer time window up to 8 h include intra-arterial thrombolysis, mechanical thrombectomy and a combination of those techniques.
Agents used for intra-arterial thrombolysis are prourokinase and tPA. These should be used within 6 h of onset of acute ischemic stroke in a large proximal vessel or up to 24 h after onset of acute basilar artery occlusion.
The use of endovascular ultrasound – called sonothrbmolectomy – has been shown to increase the recanalization rate, particularly when used in addition to tPA.
Mechanical devices can be used when intravenous or intra-arterial therapy failed or when thrombolysis is contraindicated. Contraindications include bleeding diathesis, warfarin use, elevated international normalized ratio (INR), major surgery within 14 days, thrombocytopenia, genitourinary or gastrointestinal bleeding and trauma associated with the onset of stroke symptoms.
Mechanical Strategies for thrombectomy include:
Distal clot retrieval: The retrieving device is advanced over a microcatheter through the clot and then withdrawn.
Proximal clot aspiration: The devices remove the clot from its proximal end by using aspiration methods or ultrasound.
Stentrievers: The clot is temporarily stented against the vessel wall to achieve faster reperfusion. The stent and clot can then be removed together. The stent can also be permanently deployed.
Patient positioning in relation to anesthesia machine monitors and radiology equipment requires flexibility and thinking outside the box compared to the operating room.
The anesthesia work space is often to the left of the patients head, opposed to the traditional setup with the anesthesia machine to the patient’s right.
This makes anesthesia induction an unusual procedure with the circuit coming from the left of the anesthesia provider.
The c-arm may be close to the patients head with limited access around the patient.
Frequent “runs” of the fluoroscopic x-ray equipment around the patient including the patients head with airway, breathing circuit and intravenous as well as arterial lines may pose the integrity of the anesthesia delivery and monitoring system at risk.
Line extensions for intravenous and arterial lines should be used and positioned cautiously. Attenstion should be paid to prevent pulling out of these lines unintentionally and/or unrecognized during the procedure.
The same applies to the breathing circuit, which should be extended and carefully secured.
A protective shield between the patient and the anesthesia provider protects against radiation exposure but may also be an obstacle to overcome when direct access to the patient is required. Lines and the anesthesia circuit have to be maneuvered around the shield and getting to the patient quickly may be difficult.
Vital sign monitors and equipment are often shared with the proceduralist.
Arterial blood pressure measurement may be transduced form a side port of the femoral arterial introducer sheath. However, a separate arterial line should be considered for close blood pressure monitoring during induction of general anesthesia.
Pulse oximetry is often measured from two extremities simultaneously. An additional pulse oximeter probe on the extremity with the introducer sheath may help detect perfusion defects from thrombus formation or vascular dissection.
Emergency equipment including airway management tools should be readily available. Relying on backup equipment from the main operating room may not be suitable.
Patient recovery should be in or close to the procedure area. Transporting freshly extubated patients for long distances through the vaults of a hospital may be a setup for possible disaster.
Maintain oxygen saturation >94 % 
Maintain normothermia: treat hyperthermia (temperature >38 °C) with antipyretic medications and/or cooling devices 
Patients eligible for acute reperfusion therapy must have BP controlled to <185/110 mmHg prior to, during and after reperfusion
Strategies to lower BP include the following:
Labetalol 10–20 mg IV over 1–2 min repeat x times one
Nicardipine 5 mg/h IV, titrate up by 2.5 mg/h every 5–15 min -maximum 15 mg/h
If BP not controlled or diastolic BP >140 mmHg, IV sodium nitroprusside can be used
The use of high-dose albumin is not well established.
The usefulness of drug-induced hypertension in patients with acute ischemic stroke is not well established
Hemodilution by volume expansion is not recommended
Studies favor conscious sedation over general anesthesia during endovascular therapy for acute stroke however, randomized trials do not exist 
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